A trim part, such as for a roof, is a vehicle element normally formed by superposing several layers that are joined to one another and are formed by applying heat and pressure.
As a result of this formation, a laminar element with a reduced thickness is obtained that is adapted to the shape of the inside of the vehicle body, specifically to the area of the body in which it is placed and with the function of covering the metal of said body, providing an aesthetic finish among other functions.
Thus, a trim part has a mainly aesthetic purpose, as it is an element that is seen from inside the vehicle cabin.
In addition, a roof trim part can have other functions associated to the various layers that make up its structure, such as structural, insulating or acoustic enhancement functions.
In order to improve the comfort of the vehicle cabin, a trim part can incorporate other elements in addition to those that make up its structure, providing additional functions such as illumination.
Specifically, the illumination function can encompass several different types of illumination meant to provide enough light to allow the occupants to distinguish the outline of the objects that are inside the cabin.
A reading light refers to the illumination function meant to provide enough light so that occupants can read books or documents.
When the purpose of the illumination function is to provide a decorative effect, defining visible illuminated shapes, this is referred to as a decorative light.
These functions are not mutually exclusive, so that several illumination functions can be combined in a single lighting device.
The trim part of the present invention comprises a decorative illumination function, although it optionally can also include any of the other illumination types described above.
To fulfil this illumination function meant to provide decorative lighting, it is possible to assemble on a trim part lighting devices that provide decorative light to the inside of the vehicle cabin, making these trim parts modular assemblies.
In addition, and in order to obtain more compact modular assemblies, trim parts are known that comprise the lighting devices for obtaining decorative light in which the lighting elements are not disposed assembled but as an integral part of the trim part, resulting in a compact assembly.
One of the purposes of these assemblies is to achieve a good integration of the lighting devices in the trim parts that house them, in some cases making them imperceptible when the lighting device that generates the decorative light is not on.
To achieve this goal, and considering that a trim part consists of a laminar element with a small thickness, the lighting devices must also comprise elements with a small thickness, such as for example electro-luminescent sheets or small LED light sources, which can be integrated between the various layers of the part, so that they do not significantly increase the thickness of the assembly.
These examples are illustrated by Patents EP1418090, EP2215296, DE102006012606.
In these cases in which the area to illuminate is large, the proposed solution is to use a lighting source that is able to illuminate an area as large as the area of the trim part to be illuminated, such as a set of LEDs distributed evenly in said area, or an electroluminescent panel of the same size as the trim part area to be illuminated.
Therefore, these lighting assemblies can be complex and costly for applications in which the surface to illuminate is large.
To solve this problem, it is possible to use a lighting guide element for the light emitted by the lighting source, so that the number of lighting sources or their size is not affected so greatly by the dimensions of the surface to illuminate.
In this sense are known patents JP59011934 and EP1536983, for example.
In these two antecedents the lighting source is placed on a lateral area corresponding to the perimeter of the guide element, resulting in an assembly with dimensions that exceed the perimeter of the trim itself, so that the assembly is not very compact and fragile, and requires protective element for the lighting source to prevent it from being damaged, and additional reflective elements to make full use of the light emitted by said lighting source.
This complicates the handling and/or transportation operations of the trim part, due to the protruding arrangement of the lighting sources or their protective and reflective elements with respect to the perimeter of said trim part, and can result in damage or breakage of said lighting sources.
Moreover, said protruding arrangement of the lighting sources and the other additional elements implies increasing the space occupied by the assembly, both in its transportation and when it is assembled inside the vehicle.
Therefore, the incorporation of said lighting sources inside the trim part so that they are disposed without protruding from the perimeter of the trim part and perfectly protected inside it is considered to be an improvement.
Patent DE102006012606, for example, describes solutions of this type.
In this antecedent no control is established for a localised exit of the light, as the decorative lining used consists of a translucid element that allows light to pass through it.
Therefore, in addition to a compact assembly that simplifies handling and assembly of the roof trim part with the lighting device integrated in it, the goal is a configuration of the assembly such that it allows controlling the light let out through certain areas of the trim part located appropriately, in order to obtain decorative light according to certain predefined patterns.
This control of the light outlet is established firstly regarding the versatility or customisation of light exit patterns, so that the decorative lining has localised areas that allow light to exist and areas that stop it, allowing complete freedom of design, and secondly regarding the quality, so that said light exit areas that define the light patterns are configured by perfectly defined contours which also allow diffusing the light in a uniform manner in the light exit areas.
By achieving these two objectives, namely controlling the light exit through localised areas with a uniform shape and the perfect definition of the contours of said light exit areas, the user will perceive a high-quality product, which is the ultimate objective of the present invention.